Technology and health care companies led a late-afternoon sell-off on Wall Street Wednesday, wiping out early gains for stocks.

The market had been headed higher in the early going after Pfizer and BioNTech reported updated data suggesting their potential COVID-19 vaccine may be 95% effective.

But the gains faded as traders worried anew about the economic fallout from governments across the U.S. bringing back varying degrees of restrictions on businesses in response to a recent surge in coronavirus cases.

On Wednesday:

The S&P 500 fell 41.74 points, or 1.2%, to 3,567.79.

The Dow Jones Industrial Average dropped 344.93 points, or 1.2%, to 29,438.42.

The Nasdaq composite lost 97.74 points, or 0.8%, to 11,801.60.

The Russell 2000 small-cap index gave up 22.60 points, or 1.3%, to 1,769.32.

For the week:

The S&P 500 is down 17.36 points, or 0.5%.

The Dow is down 41.39 points, or 0.1%.

The Nasdaq is down 27.68 points, or 0.2%.

The Russell 2000 is up 25.27 points, or 1.4%.

For the year:

The S&P 500 is up 337.01 points, or 10.4%.

The Dow is up 899.98 points, or 3.2%.

The Nasdaq is up 2,829 points, or 31.5%.

The Russell 2000 is up 100.85 points, or 6%.